Jimmy Fallon and Will Smith bust some moves on Fallon's first 'Tonight Show' in a hip-hop dance parody. / Lloyd Bishop, NBC

by Robert Bianco, USA TODAY

by Robert Bianco, USA TODAY

That number is what it will take for Jimmy Fallon, the sixth and latest host of NBC's Tonight Show, to top Johnny Carson's best-yet 30-year run. On the other hand, all he'll need to beat Conan O'Brien is 146 â?? a mark he seems likely to reach, given how desperately NBC wants to avoid a repeat of that quick-shift disaster, and how eager-kid personable Fallon came across Monday night.

Entering a set that seemed both more intimate and theatrical than the one Jay Leno was using when he departed, Fallon opened with a meta-self-aware "I'll be your host â?¦ for now" â?? and then proceeded to introduce himself and Tonight to anyone who had never seen either. He thanked all the former hosts, pointed out his parents in the audience ("I hope you're proud of me") and introduced his band, The Roots, and his announcer, Steve Higgins, both of whom followed Fallon over from Late Night.

While gratitude and humility are admirable traits, there were times in Monday's opening moments when Fallon risked taking them to uncomfortable extremes. One more "thank you," one more "I never thought I'd be here," and viewers might have wondered whether they wanted to be there themselves.

Luckily, he rescued the moment with one of the show's better bits. A seemingly offhand remark about an unnamed star owing him money for betting him he'd never get the Tonight Show job led to a surprise-guest parade, kicked off by Robert De Niro, that included Tina Fey, Joe Namath, Joan Rivers, Seth Rogen, Sarah Jessica Parker, Lady Gaga and - finally - Stephen Colbert.

Apparently, it's a rule that every Tonight Show host has to do an extended monologue, even though the format does not show Fallon to his best advantage. An animated delivery and vocal imitations can only carry you so far when the jokes aren't particularly funny. His strengths lie elsewhere, as in a hip-hop dancing bit he did with Will Smith that highlighted his good-sport ability to get stars to play along with him. That could also apply to musical guest U2's apparently spontaneous acoustic version of Ordinary Love, though on Tonight, it's sometimes hard to tell actual spontaneity from the TV-planned variety.

Tonight, of course, doesn't just have a new host in Fallon. After a 42-year stint in Los Angeles, it also has a new home: New York, which is where the show started. To mark the switch, U2 performed on the Rockefeller Center rooftop, as the sun set against the backdrop of the Empire State Building. It was a beautiful image no other city can match, even if that sunset did undermine the impression Tonight usually tries to create that it's airing live.

First shows of this sort usually tend to focus as much on the host as the guests, and Fallon's was no exception. And when that host is taking over what remains - even in this era of splintered viewership and declining ratings - one of TV's most storied and prestigious assignments, it's only natural that the combination of nerves and excitement can be close to paralyzing. But Fallon is an easy-to-like TV persona with a gentle style that seems well-suited to Tonight, and he'll most likely settle in.